1. Field of the Invention
The present invention relates to a method for determining the position of at least one local antenna in an examination chamber of a magnetic resonance apparatus.
2. Description of the Prior Art
In a diagnostic magnetic resonance apparatus, a local antenna is used for improvement of the signal-noise ratio. Such an antenna is matched to the size of the body region to be examined. Local antenna as known, for example, that are built fixedly into the patient table or engaged at fixed positions on the patient table for examination of the spinal column or for examination of the female breast. Also known are local antennas which are freely movable in the examination chamber, for example, flexible antennas, wrap-around antennas and extremity antennas.
The positioning of local antennas in the examination chamber of the magnetic resonance apparatus has until now ensued in most cases by means of a light-beam localizer that is fastened to the magnetic resonance apparatus at a defined distance to the center of the examination chamber. A suitable light-beam localizer is, for example, described in U.S. Pat. No. 4,629,989. After the local antenna has been applied to the patient at an optimal distance from the region under examination, the patient is positioned with the local antenna so that the center of the local antenna coincides with a light mark of the light-beam localizer. Subsequently, the patient is moved into the center of the examination chamber by the defined distance predetermined by the location of the light-beam localizer. In such a known magnetic resonance apparatus, the acquisition of the position of the local antenna is limited to the coordinate that is changeable due to the path of travel of the patient table. In the examination chamber, no further acquisition of the local antenna position ensues.
German OS 44 38 584 describes a display arrangement together with a magnetic resonance imaging apparatus, which indicates a position and an orientation of a plane in which an image is to be obtained. The display arrangement is movable, and includes a radio-frequency transmitter with several transmission coils. A tracking unit has several reception coils that receive the signal emitted by the transmission coils. From this, the tracking unit determines the location of the transmission coils.